Why in news?
In another first, scientists at the LIGO and Virgo gravitational wave detectors announced a signal from Blackhole Mergers unlike anything they’ve ever seen before – While many black hole mergers have been but this particular signal was the first where the two black holes had distinctly different masses.
- The event, dubbed GW190412, was detected nearly a year ago, and this is almost five years after the first ever detection of gravitational wave signals by these powerful detectors.
- Subsequent analysis of the signal coming from the violent merger showed that it involved two black holes of unequal masses coalescing, one of which was some 30 times the mass of the Sun and the other which had a mass nearly 8 times the solar mass.
- The actual merger took place at a distance of 2.5 billion light years away, so this event took place 2.5 billion years ago.
Significance of the Observation
- The detected signal’s waveform has special extra features in it when it corresponds to the merger of two unequal-sized black holes as compared with a merger of equal-sized black holes.
- These features make it possible to infer many more things about the characters in this celestial drama, namely, a more accurate determination of the distance from the event, the spin or angular momentum of the more massive black hole and the orientation of the whole event with respect to viewers on Earth.
- This sharp difference in mass allowed the LIGO/Virgo scientists to verify something predicted by Einstein’s General Theory of Relativity, which has so far remained untested.
- Dominant emission of gravitational waves happens at twice the orbital frequency of the binary.
- In this case, we find, for the first time, emission at a frequency that is three times the orbital frequency.
- A black hole is a region of spacetime where gravity is so strong that nothing—no particles or even electromagnetic radiation such as light—can escape from it.
- The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole.
- The boundary of the region from which no escape is possible is called the event horizon.
- A black hole can be formed by the death of a massive star.
- When such a star has exhausted the internal thermonuclear fuels in its core at the end of its life, the core becomes unstable and gravitationally collapses inward upon itself, and the star’s outer layers are blown away.
- The crushing weight of constituent matter falling in from all sides compresses the dying star to a point of zero volume and infinite density called the singularity.